Microcomputers generally comprise a processor and memory and may operate in accordance with a sequence of instructions derived from a stored program. The instructions may include a so-called "function" selected from a set of selectable functions and which define the operation which is carried out by the processor in response to that instruction. Processors may wish to communicate with external peripheral equipment including other microcomputers. For this reason, microcomputers are sometimes connected into a network with peripheral equipment or a plurality of microcomputers. This has generally been done through output ports or pins on the microcomputer and commonly these ports or pins have needed programming in order to communicate between processes on different microcomputers. Furthermore, it is conventional in microcomputers for communications, including the external communications, to occur through a bus which provides a bottleneck reducing the speed of operation of the microcomputer.
Consequently, conventional microcomputers have not provided satisfactory building blocks for use in extended networks of microcomputers. Networks have generally caused loss of speed of operation and needed additional interface hardware.